After a surprise separation last fall, Danny DeVito and Rhea Perlman are back together, PEOPLE has learned.

The beloved pair, married for 30 years and one of Hollywood's most enduring couples, have been quietly working on their relationship in recent months and have called off the separation, a source tells PEOPLE.

"They love each other," says a friend of the couple. "Always have and always will."

The cast and crew of FX's It's Always Sunny in Philadelphia celebrated the season 8 premiere at the ArcLight Cinerama Dome in Hollywood on Tuesday.

But DeVito, who plays Frank Reynolds on the series, was visibly absent from the red carpet and screening following Monday's announcement that after 30 years of marriage, the actor, 67, and Perlman, 64, are separating.